Pedro's Brushless Motor

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(1) When a magnet crosses in front of a coil of metal wire, an electric current arises while the movement of the magnet is made.

(2) When an electric current runs inside a coil of metal wire, a magnetic field is created.

This project also shows the great amplification obtained with two transistors working in a Darlington configuration.

The DC brushless motor has a disk of transparent perpex as the 'rotor' and two electromagnets as the 'stator'. On the disk (85 mm's in diameter) are two magnets (20 x 10 x 4 mm's each) at opposite ends of the diameters' disk. Each electromagnet is placed on a separate wooden stand; both at the same level of the disk shaft. One is the impulsor electromagnet and the other is the sensor electromagnet. The energy for the motor is taken from a power source of six volts, which are made up of four 1-1/2 Volt DC cells in a series circuit.

The motor does not start by itself; I will add a starter later. But when you give the disk or its' shaft a 'rotary' push of enough speed, the magnets crossing in front of the electromagnetic sensor create a current of 15 to 20 micro-amperes. This current is AC (in reality are pulses) and needs to be rectified. These pulses are rectified to be only positive pulses with a diode and then taken to the base of the first Darlington Transistor Amplifier. The few micro-amperes first obtained are now transformed to 40 to 50 mili-amperes that drives the electromagnet impulsor. This electromagnet impulsor gives magnetic pulses that react with the magnet in front of it at the precise moment, to produce a 'rotary-push' that maintains the disk turning while the battery provides the current.

Practical 'brushless motors' are of a form quite different from this one. This is a didactic experimental laboratory motor. DC brushless motors are constructed of many different sizes and powers...from small and tiny motors to powerful industrial motors that can even run a railroad locomotive.

I hope this project will inspire you to practice with magnets, electromagnets and transistors!

My thanks to Elisenda Escudero, my daughter and Juan Antonio Gomez, her husband, that made the photos for this webpage and the treatment of images. My special thanks are given to my friend Patrick Cambre, who so carefully mounted this webpage.